THE tragedy in operating theatre eight at Bankstown–Lidcombe Hospital in July 2016, where one baby died and another was seriously injured, shows just how dangerous nitrous oxide can be.

At Bankstown–Lidcombe, a series of errors led to the failed resuscitation of two babies with nitrous oxide instead of oxygen. These events were reported with varying degrees of accuracy in the news media, but the final report into the incident has been released. And it’s a study on how a series of system and human errors can line up to result in serious harm.

Reading the Chief Health Officer’s report is a chilling experience for anyone who’s been involved in the resuscitation of a newborn. But visceral reactions aside, as with most medical error, there were a lot of small things that went wrong for this incident to play out the way it did – and there’s a lot we can learn from it.

Nitrous oxide is a gas commonly found in hospitals – it’s so common that most of us probably don’t even notice it. But it’s also the only anaesthetic gas that’s pumped directly through hospital pipes to wall outlets and patients, without first necessarily passing through a gas analyser.

All other anaesthetic gases, such as those used to keep patients “asleep” during surgery, are first passed through an anaesthesia machine and analysed for content. Nitrous oxide in cylinders is analysed prior to filling, and each cylinder is colour-coded. Indeed, nitrous oxide pumped through anaesthesia machines, whether through wall outlets or via cylinders, is directly analysed in real-time.

Anaesthesia machines also have built in safety features that automatically shut off nitrous oxide delivery if there’s a loss of oxygen supply, because breathing 100% nitrous oxide will always result in hypoxia.

So the lesson to learn here is in fact an old one: where error can happen, it will happen. This is a lesson learned over and over in high-risk industries with many moving parts – such as medicine. The challenge is trying to understand how to stop errors like this from ever occurring again.

But to do that we have to understand how this disaster could happen in the first place, which takes us back to January 2014. Then, a baby born on the delivery suite needed extra oxygen and the oxygen cylinder being used ran out. Not a good thing to happen.

So a decision was made to install piped outlets for oxygen into the birthing suite and then also into the neonatal resuscitaires in the operating theatres. It’s in the implementation of this plan when it appears that things started to go wrong.

The report highlights two key junctions where the next set of errors were able to occur and result in catastrophic harm.

The technique used to actually cut the lines and install new pipes was done incorrectly. The expert engineer noted in the report that all the medical gases, including nitrous oxide, were isolated during the works, rather than only the pipe being worked on. This meant that if a pipe other than oxygen was cut, there would be no immediate warning in the form of pressurised gas escaping the pipeline.

This risk was further compounded because the nitrous oxide pipe had been mislabeled as oxygen 20 years ago – when the ceiling pipes to the operating theatres were originally installed – so it’s very likely that the technician thought that they were cutting the correct pipe.

Then, once the faulty installation was complete, the procedures for testing weren’t followed. The Australian safety standard AS 2896-2011 requires a delegated anaesthetist to analyse the gas output from any new installation.

No member of the anaesthesia department was made aware that the installation was even happening.

But humans are notoriously bad at performing mundane or repetitive tasks, such as gas installation and analysis, without error. They’re even worse at it if they’re fatigued or the work is done overnight, as happened here.

So as long as nitrous oxide is plumbed next to oxygen and can be delivered to patients without real-time analysis, the opportunity exists for this to happen again. If the nitrous oxide piping had never been in the wall, the worst possible error would have been the delivery of air instead of oxygen. Not ideal, but probably not deadly.

And if all the wall outlet gases were passed through an analyser every time, this would have been an annoying near miss, resulting in someone getting an oxygen cylinder or using a different outlet.

Nitrous oxide is a useful gas with some excellent properties, but it’s time to choose. Either we change our practice so this error can never lead to harm again, or we get rid of the not-so-happy gas.

Dr Simon Hendel is a Melbourne-based anaesthetist and retrieval physician. He is completing his postgraduate studies in journalism.

One thought on “Nitrous oxide: learning an old, hard lesson”

One can go even one step further back. There is a culture in modern medicine of excessive and over management of low level risks, presumably bought about through fear of litigation. This would appear to be one such case. The initial precipitant for this whole sorry saga was the running out of the oxygen cylinder on the resuscitation trolley. This is undeniably an untoward event, and the report into the incident details how the trolley and infant were relocated across the corridor to the special care nursery to continue the resuscitation. This may have been a calm orderly process, but somehow I doubt it. It was far more likely to be carried out with a great deal of agitation and profanity.

Risk management processes are a pyramid, one employs the lowest action on the pyramid to reduce the risk to an acceptable level, not necessarily eliminate it all together (eliminate the hazard is in fact at the very top). “Use personal protective equipment” is at the bottom, followed by “Institute administrative controls”. In this case we have had either “modify systems”, or “substitute” employed (third and second from the top respectively ), in fact they are a bit of both. The hospital decided to modify the system by substituting piped gas for cylinders. Of course cylinders would still have to be present in case the piped supply ever failed, so it mostly fits as a modified system.

Was there however a case for a lower level strategy? I believe there was. PPE isn’t relevant here, but an administrative contol in the form of a directive that cylinders on resuscitation trolleys must be checked regularly (once a shift, or daily), and after any resuscitation, as well as ensuring a readily accesible supply of fresh cylinders would have also reduced the risk to acceptable levels. Instead an expensive, and then poorly conducted works programme was embarked on. One that failed to have a formal risk assessment conducted prior to it’s implementation, was conducted improperly, and thus exposed the institution to the small, but known risk of a gas misconnection. And the programme will be even more expensive once the damages payments to the two families affected by this terrible tragedy are added in. This should be a salutory lesson to health administrators everywhere. Over manage risk at your peril.